Photocatalytic degradation of oxytetracycline with the REMs (Er, Tm, Yb)-doped nickel and copper aluminates

Oxytetracycline (OTC) is an antibiotic drug. It is widely used in veterinary, animal husbandry, and agriculture. Antibiotics are emerging environmental pollutants. We propose an efficient photocatalytic method for remediation of aqueous reservoirs from OTC. We synthesized erbium-, thulium- and ytterbium-doped nickel and copper aluminates. The doped samples have better dispersion, higher specific surface areas (188 m2 g−1 for Er-NA) and decreased energy band gaps. The doping of nickel and copper aluminates (NA and CA) significantly improved the photocatalytic performance. Er-CA was the most photoactive. The Er-doping of NA and CA increased photodegradation efficiency from 27 to 73 % and from 65 to 90 %, respectively. The LC-MS analysis allowed to identify the major intermediates of OTC photodegradation. The photocatalytic metabolites were hemocompatible and did not present cytotoxicity towards monocytic cells. We envisage a great potential of the rare-earth-metal-doped semiconductors in the removal of emerging environmental pollutants.